add incremental/debug test for autodiff

Author: ZuseZ4

tests/ui/autodiff/incremental.rs

@@ -0,0 +1,41 @@
+//@ revisions: DEBUG RELEASE
+//@[RELEASE] compile-flags: -Zautodiff=Enable,NoTT -C opt-level=3 -Clto=fat
+//@[DEBUG]   compile-flags: -Zautodiff=Enable,NoTT -C opt-level=0 -Clto=fat -C debuginfo=2
+//@ needs-enzyme
+//@ incremental
+//@ no-prefer-dynamic
+//@ build-pass
+#![crate_type = "bin"]
+#![feature(autodiff)]
+
+// We used to use llvm's metadata to instruct enzyme how to differentiate a function.
+// In debug mode we would use incremental compilation which caused the metadata to be
+// dropped. We now use globals instead and add this test to verify that incremental
+// keeps working. Also testing debug mode while at it.
+
+use std::autodiff::autodiff_reverse;
+
+#[autodiff_reverse(bar, Duplicated, Duplicated)]
+pub fn foo(r: &[f64; 10], res: &mut f64) {
+    let mut output = [0.0; 10];
+    output[0] = r[0];
+    output[1] = r[1] * r[2];
+    output[2] = r[4] * r[5];
+    output[3] = r[2] * r[6];
+    output[4] = r[1] * r[7];
+    output[5] = r[2] * r[8];
+    output[6] = r[1] * r[9];
+    output[7] = r[5] * r[6];
+    output[8] = r[5] * r[7];
+    output[9] = r[4] * r[8];
+    *res = output.iter().sum();
+}
+fn main() {
+    let inputs = Box::new([3.1; 10]);
+    let mut d_inputs = Box::new([0.0; 10]);
+    let mut res = Box::new(0.0);
+    let mut d_res = Box::new(1.0);
+
+    bar(&inputs, &mut d_inputs, &mut res, &mut d_res);
+    dbg!(&d_inputs);
+}